Do I have to c-notch when doing a rear flip kit?

[slam59]

I have a 74 c10 and was told by a friend that i might have to do a c-notch if i do a flip kit. I see on here that so many have done a flip kit on the rear and never mention that they had to do a notch. Some say they remove their rubber stops. Is he correct? I want to for the time being do 3" drop coils in front and a flip kit in the rear.